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20 BIOLOGICAL AND SOCIAL UNIVERSALSincreases in activation into or through adolescence during performance of a virtualreality spatial navigation task (Pine et al., 2002) and an oculomotor responsesuppressiontask (Luna et al., 2001).Implications of Adolescent-Associated NeuralTransformations for Normal and AtypicalAdolescent BehaviorsAdolescent sculpting in PFC and interconnected regions such as the cerebellumis seemingly related to the gradual emergence of mature cognitive capacities, includingimprovements observed during adolescence in aspects of executive function,response inhibition, attentional capacities, memory function (Casey et al.,2000; Luna et al., 2001; Pine et al., 2002), as well as emotional self-control (e.g.,Dahl, 2001). Mesocorticolimbic brain regions undergoing particularly dramaticchange during adolescence also form critical parts of the stress-sensitive neuralcircuitry implicated in modulating risk taking, novelty seeking, and social behaviors(e.g., Le Moal & Simon, 1991), and in assigning hedonic affect (e.g., Volkowet al., 2002) and attaching incentive motivation (Robinson & Berridge, 2003) tonatural rewards (including social stimuli and novelty), drugs of abuse, and cuesassociated with these rewards. The postulated attenuation in mesolimbic DA activityassociated with a shift towards greater mesocortical activation early in adolescencelikewise may be motivationally significant, given that functionalinsufficiencies in mesolimbic DA terminal regions have been linked to a rewarddeficiency syndrome characterized by actively seeking out drugs of abuse as wellas “environmental novelty and sensation as a type of behavioral remediation ofreward deficiency” (Gardner, 1999, p. 82). To the extent that a mild version ofthis syndrome is fostered by normal developmental transitions occurring early inadolescence, young adolescents likewise might pursue novelty, drugs, and otherstimuli to counter a mild and partial anhedonia. Indeed, reports of feeling “veryhappy” drop by 50% between childhood and early adolescence, with adolescentsalso experiencing positive situations as less pleasurable than adults (Larson &Richards, 1994). This possibility is highly speculative, however, with others arguingthat activity in mesolimbic DA systems is positively associated with drugseeking (e.g., Spanagel & Weiss, 1999). Moreover, most of the work suggestinga shift in balance among mesocorticolimbic DA terminal regions has been derivedfrom work with laboratory animals, and it remains to be determined how well thesefindings represent developmental events occurring in human adolescents. Nevertheless,given the developmental transformations that occur in mesocorticolimbiccircuitry, it would be surprising if adolescents did not differ from mature animalsin their motivated behavior and the way that they respond to natural rewards anddrugs of abuse. And they do.